Beyond the visual word recognition stage, how does reading continue? Most current models consider that information processing takes two parallel paths. One leads to access to the lexicon and meaning of words, the other to their phonological representation.
Neuropsychology (Marshall & Newcombe, 1973) provided the first clues to this two-way organization: in addition to peripheral alexias, which include pure alexia, neuropsychology distinguishes at least one form of deep or central alexia, in which the patient has partial access to the meaning of the word without recovering its pronunciation, and a form of surface alexia, in which errors reflect over-regularization with the application of grapheme-phoneme conversion rules without understanding the word.
Marshall and Newcombe, then Coltheart, proposed that these deficits reflect the selective deterioration of at least two reading pathways, a surface pathway that enables grapheme-phoneme conversion of all character strings, and a deep pathway that retrieves the lexical-semantic information associated with each word. According to this model, various factors modulate the use of one or the other pathway. Three essential categories of strings can be distinguished :
- pseudowords such as "bakifo" (surface path only) ;
- regular words such as "bateau" (surface and deep path) ;
- irregular words such as "onion" (deep path only).
